Variable pitch fropeller mechanism for aeroplanes and the like



A N 5 132. J, R, ZlPAY 1,852,500

VARIABLE PITCH PROPELLER MECHANISM FOR AEROPLANES AND THE LIKE Filed March 18, 1950 INVENTOR Patented Apr. 5,1932

UNITED STATES PATENT OFFICE JOHN RAPE ZIPAY, 'OF PITTSBURGH, PENNSYLVANIA Application filed March 18, 1939. Serial No. 436,748.

In the case of variable pitch propellers the blades are rotatable on their longitudinal axes so that their pitch may be adjusted.

I provide improved means for attaching a the blades to the propeller bushing or like element whereby the tendency of the blades to break at their point of connection and their tendency to become released from thelr attachment are counteracted.

For these purposes I provide a new and improved means for rotatably Inountmg the blades relative to the propeller bushing or like element and I also provide new and improved means for counterbalancing the blades to assume the torque.

Again where the stems of the propeller blades are mounted in relation to the propeller bushing or like element there is danger iii of fracture at the point of engagement of the stems of the blades with the bushing or like element.

For the purpose of counteracting this tendency I provide properly positioned counterbalancing weights.

Again as the speed of the-propellers in creases it is desirable to increase the pitch of the blades, thus increasing the driving force of the latter, and, on the other hand, as the speed decreases the pitch of the blades should be lessened.

Therefore I provide novel means comprising properly located counterbalancing weights which, as the speed increases, automatically increase the pitch of the propeller blades and which, as the speed decreases, automatically decrease said pitch.

Furthermore it is important that the operator of an aeroplane be provided with con- 40 venient means for varying the pitch of the propeller blades at will to meet the varying requirements of taking-off, flying and landing.

For this purpose I provide new and improved means whereby the operator may vary the propeller blade pitch at will and also whereby he may adjustably limit or regulate the increase of pitch of the blades as speed increases.

Other novel features of construction, and

propeller bushing removed and portions of the mechanism shown in section, the propeller blades being broken off.

Fig. 3 is a side view of one of the counterbalance weights, the same being shown on smaller scale than in Fig. 2 and the stem of the propeller blade being shown in cross section.

Fig. 4 is an enlarged View of themanually operated control mechanism, the view being partially in plan and partially broken away in longitudinal section.

Referring to the drawings, 1 represents the 76 front portion of the fuselageof an aeroplane and 2 the propeller shaft which is driven in the usual manner as by the motor 2a. The shaft 2 extends forwardly from the motor and has mounted on its outer or front-end the 80 transversely disposed and partible propeller bushing which comprises the parts 3a and 3b, the plane of parting being at right angles to the axis of the propeller shaft. The bushing parts are clamped together by means of clamping straps 4 which may each be formed of two hingedly connected parts with their free ends tightened together by bolts 5.

The straps preferably engage circumferentially disposed grooves in the bushing parts to preventilateral slipping or movement of the straps after they are tightened in place.

The bushing part 3a is provided with a rearwardly extending tubular boss 6 which fits over the shaft 2. The central portions of the bushing parts are solid or non-cavitated' and are provided with registering bores to. receive the shaft 2, the shaft and the bores of the boss and the bushing parts being tapered to fit and the feathers 7 being used to" no hold the bushing fixed relative to the shaft. The nut or nuts 8 are screwed up on the end of the shaft 2 against the flat end of the tubular boss 9 on the bushing part 36. a

' At either side of their central portions the bushing parts 30 and 3b are cavitated to form, when the bushing parts are assembled, cylindrical bores in which the stems of the propeller blzfiies 11 are journaled. I v

I provide novel and improved means for 'ournaling the stems 10 of the propeller lades 11 in the propeller bushing 3a-3b and for preventing the accidental withdrawal of the stems from the bushing.

Thus the end bores of the bushing 3a-3b are provided adjacent to their outer extremities with annular seats 12, the outer walls of said seats forming the inwardly extending v annular lips 13 at the outer ends of the bushing. Spaced inwardly from the seats 12 are similar seats 14, thus leaving between each pair of seats 12 and 14 an annular internal shoulder 15.

The journal portion of each of the stems 10 comprises the reduced inner and threaded end 16, next to the latter an annular shoulder 17 which, when the propeller structure is assembled, is alined with the seat 14, next to the shoulder 17 a reduced neck 18 and next to the neck 18 an annular shoulder 19 similar to the shoulder 17 and alined with the seat 12. Next to the shoulder 19 is a shoulder 20 of greater diameter which rotates within the lip 13 but does not contact therewith.

21 is a tapered roller bearing assembly whose outer member is contained in the seat 14 while its inner member is of proper diameter to be slipped on the shoulder 17. 22 is a similar bearing assembly with its outer member contained in the seat 12 while its inner member is mounted on the shoulder 19.

The planes of parting of the two bearings converge toward the axis of the journal, as shown at the right in Fig. 2.

23 represents a holder-ring which is split or parted diametrically and which is fitted loosely on about the neck 18 of the journal, the parts of the holder-ring being held against separation by the encircling sleeve 24; which is tight between the bearing members.

The parts of the holder-ring 23 are provided with hub flanges 25 extending towards either side and which bear against the sides of the shoulders 17 and 19 and thus hold the body of the ring out of frictional contact with the roller bearings.

The inner threaded end 16 of the journal has applied thereto the lock nuts 26 and 27 with the interposed washer 28.

As an additional safeguard against the ac cidental unscrewing of the nuts from the journal, the bore of the bushing 3a-3b is made short enough to clear the end of the journal but too short to permit the nuts to drop oil the end of'the journal.

to the bushing even if the nuts Oligtlle inner end of the journal be absent. g

Outside of the shoulder 20 the stem of the prodpeller blade 11 is provided with a v0 ncal surface 29 which is provided wi h okey'seats.

t is apparent that an the holder-ringwill prevent longitudinal movement of the propllerblades relative 30 represents a counter-balancing .weight formed on or attached to the outer end of a lever 31 whose inner end is provided with a split collar 32 which encircles the portion 29 of the stem 10, and said collar isclamped in place by means of the usual clampin bolt.

The collar is provided with a' ey seat which registers with a key seat on the portion 2 9 of the stem, a key 33 being held in the registering seats when the collar is clamped on the stem.

The counterbalancing weights are set in position so as to compensate for the torque exerted on the journals by the bite of the propeller blades on the air.

Thus when the propeller blades revolve clockwise the weights are in front, as shown in Fig. 1, but if the propeller blades revolve counterclockwise the weights are set at the rear.

The weights thus serve to counterbalance the torque and revent fracture of the stems which is otherwise likely to occur at the point where they enter the bushing. This tendency is particularly marked in the case of heavy metal propeller blades.

The placing of the counmrbalancing ,weights at the blade end of the journals of the propeller blades accomplishes an important result in counteracting the torque. If the weights were placed at the inner or propeller shaft ends of the journals the action of the weights would be effective to apply an increased torque or twist to the blades. By placing the weights at the points indicated this torque is assumed and no twist is efiective on the journals.

Again, the weights act to automatically regulate the pitch of the propeller blades in relation to their speed of revolution. As the speed of the blades increases, the weights, by their inertia, rotate the blades on their longitudinal axes and increase their pitch. Likewise the weights tend to rotate the blades in the opposite direction as the speed decreases and thus reduce their pitch. The weights are arranged to work against the influence of a spring or springs.

34 represents cranks whose inner ends are provided with split collars 34 which are clamped on and keyed to the cylindrical surfaces 29 of the stem 10 between the weights and the ends of the propeller bushing. These cranks are oppositely disposed, as shown in Fig. 1, and are set at 90 from the weights.

The outer ends of said cranks are connected by the links to the yoke members 36 fixed on the front of the head 37 of a sleeve 38 slid ably mounted on the propeller shaft 2. The sleeve 38 rotates with said shaft.

39 represents a helical spring, preferably of spiral form, coiled about the shaft 2 between the sleeve 38 and the boss 6 of the propeller bushing.

40 represents a disk rotatably mounted on the rear end of the sleeve 38 in any convenient manner. ll represents a lever having a forked end which straddles the shaft 2 and bears against the rear face of the disk 40. The lever 41 is pivotally mounted intermediate of its ends as at 42 to the front of the motor. The other end of the lever 41 is connected by the universal joint 43 to the front end of a cable 44 whose other end is connected by the universal joint and nut 45 to the end of a sleeve 46 which is slidably mounted in a barrel 47 which in turn is fixedly supported as by the bracket 48 from a convenient por tion of the fuselage. The sleeve is prevented from rotation in the barrel as by the screw 49 fixed in the barrel engaging a longitudinally disposed groove or slot in the wall of the sleeve.

A threaded nut 50 is fixed in the inner end of the sleeve 46 and has screwed therein the screw shaft 51. The shaft 51 is held against longitudinal movement relative to the barrel by the ball-bearing 52, whose inner member is fixed on the shaft and whose outer member is held between the internal shoulder 53 in the bore of the barrel and the cylindrical plug nut 54 screwed into the threaded end of the bore.

inner and outer races held in said recess with the outer races seated in the respective grooves, a propeller blade for each end of the bushing having a shank entering the recess and fitting in the inner races of the bearings therein, means to hold the bushing halves to gether, means carried by the shank and extending through the bushing to adjust the blades, a threaded end on the shank projecting inwardly of the recess through the inner bearing, an adjusting nut on said threaded end bearing against the inner race of the inner bearing, and means to hold said nut in adjusted position .on the shank.

Signed at Pittsburgh, Pa., this 15th day of March, 1930.

JOHN RAPP ZIPAY.

The outer end of the shaft 51 has secured I thereon, as by nut and key, the hand wheel 55. By turning the hand wheel in the proper direction the sleeve may be extended from or retracted relative to the barrel, thus operating the forked lever.

The spring 39 and the weights 30 are set to work against each other. Thus as the speed of revolution of the propeller blades increases the inertia of the Weights will tend to compress the spring and rotate the propeller blades to increase their pitch but as the speed decreases the expansion force of the spring will tend to decrease the pitch of the blades.

The operator by adjusting the sleeve 46 in the barrel 47 may re ulate the minimum pitch of the blades by limiting the expansion of the spring, and may increase the pitch of the blades at speeds too low to operate the centrifugal weights.

The protruding end of the sleeve 46 is preferably provided with a graduated scale, as at 56, so that the operator may be advised of the 

